CEL comes on then goes off after 2-4 seconds.

[gsxjoe]

I have an odd problem. Over the last week or so I have had my CEL come on then go off after 2-5 seconds while driving in 1st or 3rd gear, usually around 2500-3000 rpm. This has started, it seems, after I had fixed the plug that connects to the coolant temp sensor. Whoever owned the car before me took the wire and just stuck it through the hole and wrapped the conductors around the metal clip.

Brief history on the car.
I bought the car last November after searching high and low for the perfect project to work on while I go to school. Most of the mods in my profile are ones that were on the car prior to me purchasing and there are still a lot of unknowns. From what I was told when I bought it was that the owner prior to the person I bought it from had had the engine rebuild and drove it for about a week before he got his license suspended and so he sold the car to the kid I bought it from. Most of the information that I have gathered was second had or from me looking up serial numbers on the web.

I have replaced the water pump and timing belt, changed the oil and put new plugs in so far as well as fixing misc. electrical issues (bad grounds, frayed wires, etc.) From the research that I have done so far on the forums, I have learned that my alternator is going bad (tested battery with car running and high-beams on) Have 13-14 volts running and 9-10 with high-beams on. I also need to get rid of this SAFC and get DSMLINK.

Would a bad alternator or electrical connections cause the CEL to come on while driving then go off? There is one other connection that seems to be a little loose, it is the connection closest to firewall on throttle body, closed throttle position switch?

Thanks for the help in advance, in the meantime I am going to keep searching these forums and see if I can find anymore information.

 

[MY1GDSM]

What all is happening when the CE light comes on? First step would be to Pull the Code...
Do you have a logger? if not you can pull the codes this way Click here

 

[gsxjoe]

Guess I forgot to add that part in, my apologies. Nothing really happens that is noticeable beside the light coming on then going off. Besides the car running really rich and the oil pressure stays low at a stop and goes up to first mark when driving, which I believe is normal. I have not noticed any type of hesitation or anything like that. I'll go drive around the block and see if it pops on again.

I was under the impression that I could not pull a code unless the CEL was on all the time.

 

[MY1GDSM]

Codes are saved...Though Not everything will set a code of right away say like a Bad o2 and
Some things that set a code won't keep the CE lit unless it stays a problem.

IE: If you go out with your car running an unplug your Maf the CE will light up but if you plug it back in the light will go off.

But, The code is retained as long as the Ecu continues to have power or is cleared by other means.

 

[gsxjoe]

Awesome info. I just got back from hooking a analog meter and counting the pulses and they are all short, which means normal from the link that you posted. I am assuming that I would have to get some kind of OBD1 logger to see if any codes are stored?

 

[necrotopsy]

i think if you go to atozone they will read the code for you for free. i know they will for obdII, not positive about obdI

 

[gsxjoe]

The Autozone by my house told me that the light would need to be on to check for any codes and the dealership told me I would need to fork over 125 big ones for a diagnostic. Would that be worth it or should I apply my cash towards a datalogger of some sort like the palm ones I keep seeing?

 

[crazyquik22023]

if the check engine light goes on for a few seconds and then goes off right away it is most likely either 1 of 2 things, either it is coming on for knock or from overheating, If you have a stock ecu on the stock settings the CEL will come on if you car gets above i believe 226 deg or if you are experiencing 2 deg or more of knock ret. both of these can not be read on a datalogger or handheld obd-II device.

 

[BigBeans]

Put the money towards link. After you have it you won't know how you lived without it.

For some reason i was thinking the OP had a 2G. Default CEL is 5 counts for us 1G guys, so it would have to be MAJOR phantom knock. OP you could always check the knock sensor, if the back is gooey it needs replacement.

 

[crazyquik22023]

Put the money towards link. After you have it you won't know how you lived without it.

For some reason i was thinking the OP had a 2G. Default CEL is 5 counts for us 1G guys, so it would have to be MAJOR phantom knock. OP you could always check the knock sensor, if the back is gooey it needs replacement.

oops, my fault i thought it was 2 deg, he also could be overheating right at the limit that makes the CEL come on and it just goes off b/c he keeps dropping below the CEL temp. But I agree also get DSMLink, it's def. worth it

 

[BigBeans]

oops, my fault i thought it was 2 deg, he also could be overheating right at the limit that makes the CEL come on and it just goes off b/c he keeps dropping below the CEL temp. But I agree also get DSMLink, it's def. worth it

Only reason i doubt that is because he says it happens at low RPM. If it was on the threshold of overheating, it would be happen after some time in boost, not just putting around town.

Not a bad idea though, i've see this happen on my car (with the CEL set lower than stock) during dyno sessions.

 

[gsxjoe]

Thanks for the info. Seems that it comes on while I'm not generating any boost. I'll check and make sure my knock sensor is alright and take it for a test drive in bit and see if I can find any other conditions that cause the CEL.

 

[MY1GDSM]

crazyquik22023 & BigBeans

Since when does a Stock ecu flash the CE light for Knock???

Also crazyquik22023 the OPs car is ODB I and you can see if the coolant temp is high pretty easily

 

[gsxjoe]

Just drove down the street, not generating any boost, vacuum at about 15% (according to boost gauge) CEL came on for a few seconds then went off then the car backfired. Would my timing cause something like this?

 

[MY1GDSM]

(according to boost gauge)

Is this a aftermarket gauge? Because the Stock gauge is not are real gauge but a calculation based off of airflow and not even close to accurate unless you of 0 pressure loss(not likely)...

 

[BigBeans]

crazyquik22023 & BigBeans

Since when does a Stock ecu flash the CE light for Knock???

I know the stock ECU can turn on the CEL for knock.

I always thought it turned on as you went beyond 5 counts in stock form. I know that's the default setting in link, and i thought it was a standard ECU function, but i could be wrong.

 

[MY1GDSM]

I know the stock ECU can turn on the CEL for knock.

I always thought it turned on as you went beyond 5 counts in stock form. I know that's the default setting in link, and i thought it was a standard ECU function, but i could be wrong.

Either You know or you don't.

Yes it's a function of Ecm/Dsmlink But it's not of a of a Stock Ecu(or stock coding)...

I guess burning a eprom chips that turn the boost gauge into a knock gauge is pointless... .

 

[BigBeans]

Either You know or you don't.

Yes it's a function of Ecm/Dsmlink But it's not of a of a Stock Ecu(or stock coding)...

I guess burning a eprom chips that turn the boost gauge into a knock gauge is pointless... .

The stock ECU can throw a code for knock, and trigger the CEL. This part i know.

I thought it could turn the CEL on momentarily, while exceeding 5 counts of knock, the same way it works with the default setting on link. If it can't, my bad.

Maybe someone can clarify?

 

[gsxjoe]

Just got back from having dinner and on the way home all was well for the most part. No CEL while driving. I did however attempt to give it a little gas and the power seems to be lacking. My turbo didn't kick in like it usually does and upon pulling into the driveway I believe I heard a ping noise then the CEL popped on and the car died. I restarted the car and let it idle for a minute or two and the CEL did not return. I'm starting to wonder if my timing is out of wack. I pulled a plug before I left and it was covered in black carbon, dry not wet and my oil level is good. Plugs are NGK BPR7ES in case anybody was wondering.

Is this a aftermarket gauge? Because the Stock gauge is not are real gauge but a calculation based off of airflow and not even close to accurate unless you of 0 pressure loss(not likely)...

Autometer boost/vacuum gauge.

 

[gsxjoe]

After testing my car on the road for the past week and trying to come up with a answer to why my CEL keeps coming on and then going off, I noticed that when it comes on I can hear a clicking noise. I also found an exhaust leak at my catback, right after the cat, one of the bolts vibrated loose. I tightened everything back down but I am still getting the CEL at random times. What is the best advice for trying to find this problem? I checked the knock sensor, seems good and according to the SAFC that I have my O2 sensor voltages are good. (although I really can't trust that POS) Does anybody think I might have a bad ground somewhere?

 

[brownfinger]

You really need to get a hold of a datalogger and find out what the code is. Plus, the logger will help you tune the SAFC, to eliminate the rich condition.

My 92 does something similar to what you're describing. It'll start misfiring or bogging, the CEL comes on, and then goes out and the car runs normal. At worst, I shut it off and turn it back on and it's normal. The code stored is always 44: ignition coil circuit. It did this before and after I replaced the coil, transistor, and plug wires. Since that's the entire ignition system, it's either the harness or the ECU. The clicking sound is often indicative of a failing ECU. You should pull the ECU and inspect the caps.

 

[gsxjoe]

You really need to get a hold of a datalogger and find out what the code is. Plus, the logger will help you tune the SAFC, to eliminate the rich condition.

My 92 does something similar to what you're describing. It'll start misfiring or bogging, the CEL comes on, and then goes out and the car runs normal. At worst, I shut it off and turn it back on and it's normal. The code stored is always 44: ignition coil circuit. It did this before and after I replaced the coil, transistor, and plug wires. Since that's the entire ignition system, it's either the harness or the ECU. The clicking sound is often indicative of a failing ECU. You should pull the ECU and inspect the caps.

Thanks, I will look into that. I found a wire and connector that leads to the throttle body earlier today, the one closest to the firewall was only held on my 1 or 2 conductors so I pulled it off, restripped and put a new connector on it. Then for some unknown stupid reason I had unplugged the cam angle sensor and forgot to plug it back in when I started the car, now I'm getting idle surge and permanent CEL. Guess that is kind of a blessing in disguise. At least now I can pull codes and hopefully get to the bottom of this. Again, thanks to everybody for the tips and advice, much appreciated

 

[crazyquik22023]

Either You know or you don't.

Yes it's a function of Ecm/Dsmlink But it's not of a of a Stock Ecu(or stock coding)...

I guess burning a eprom chips that turn the boost gauge into a knock gauge is pointless... .

A stock ecu still throws a code for knock... I'm not positive how much knock it needs to throw a code on a stock ecu but it will still throw a code for it.

 

[And_44]

I may of misread a post or two of yours OP, but if I understood wrong I'm sorry.

I had an issue where my ECU would throw an CEL and it would go off again and would hear a single click for on then off and car would die for a very slight second, but turned out it was my battery terminals being old and coming loose. Also the battery wasn't being held down. So under any type of mild acceleration or deceleration or bumps, turns, any sudden movement period. My ECU would power down and then back on. No codes where stored because the ECU just saw a loss of power. Nothing mechanical or electrical was wrong, just the terminals of battery needed to be replaced, and battery properly held down.

 

[triggerx]

BTW It could just be the ecu in general. Had a similar problem but I just swapped the ecu and problem solved.

However it was ### the ecu was throwing a code for an injector issue